Merge pull request #565 from mcarton/or_fun_call

Handle Entry types in OR_FUN_CALL lint

src/methods.rs

@@ -9,7 +9,10 @@ use syntax::codemap::Span;
 
 use utils::{snippet, span_lint, span_note_and_lint, match_path, match_type, method_chain_args, match_trait_method,
             walk_ptrs_ty_depth, walk_ptrs_ty, get_trait_def_id, implements_trait};
-use utils::{DEFAULT_TRAIT_PATH, OPTION_PATH, RESULT_PATH, STRING_PATH};
+use utils::{
+    BTREEMAP_ENTRY_PATH, DEFAULT_TRAIT_PATH, HASHMAP_ENTRY_PATH, OPTION_PATH,
+    RESULT_PATH, STRING_PATH
+};
 use utils::MethodArgs;
 use rustc::middle::cstore::CrateStore;
 
@@ -343,19 +346,31 @@ fn lint_or_fun_call(cx: &LateContext, expr: &Expr, name: &str, args: &[P<Expr>])
         or_has_args: bool,
         span: Span
     ) {
+        // (path, fn_has_argument, methods)
+        let know_types : &[(&[_], _, &[_], _)] = &[
+            (&BTREEMAP_ENTRY_PATH, false, &["or_insert"], "with"),
+            (&HASHMAP_ENTRY_PATH, false, &["or_insert"], "with"),
+            (&OPTION_PATH, false, &["map_or", "ok_or", "or", "unwrap_or"], "else"),
+            (&RESULT_PATH, true, &["or", "unwrap_or"], "else"),
+        ];
+
         let self_ty = cx.tcx.expr_ty(self_expr);
 
-        let is_result = if match_type(cx, self_ty, &RESULT_PATH) {
-            true
-        }
-        else if match_type(cx, self_ty, &OPTION_PATH) {
-            false
+        let (fn_has_arguments, poss, suffix) =
+            if let Some(&(_, fn_has_arguments, poss, suffix)) = know_types.iter().find(|&&i| {
+                match_type(cx, self_ty, i.0)
+            }) {
+                (fn_has_arguments, poss, suffix)
             }
             else {
-            return;
+                return
             };
 
-        let sugg = match (is_result, !or_has_args) {
+        if !poss.contains(&name) {
+            return
+        }
+
+        let sugg = match (fn_has_arguments, !or_has_args) {
             (true, _) => format!("|_| {}", snippet(cx, arg.span, "..")),
             (false, false) => format!("|| {}", snippet(cx, arg.span, "..")),
             (false, true) => format!("{}", snippet(cx, fun.span, "..")),
@@ -364,13 +379,14 @@ fn lint_or_fun_call(cx: &LateContext, expr: &Expr, name: &str, args: &[P<Expr>])
         span_lint(cx, OR_FUN_CALL, span,
                   &format!("use of `{}` followed by a function call", name))
             .span_suggestion(span, "try this",
-                             format!("{}.{}_else({})",
+                             format!("{}.{}_{}({})",
                                      snippet(cx, self_expr.span, "_"),
                                      name,
+                                     suffix,
                                      sugg));
     }
 
-    if args.len() == 2 && ["map_or", "ok_or", "or", "unwrap_or"].contains(&name) {
+    if args.len() == 2 {
         if let ExprCall(ref fun, ref or_args) = args[1].node {
             let or_has_args = !or_args.is_empty();
             if !check_unwrap_or_default(cx, name, fun, &args[0], &args[1], or_has_args, expr.span) {

src/utils.rs

@@ -20,10 +20,12 @@ pub type MethodArgs = HirVec<P<Expr>>;
 
 // module DefPaths for certain structs/enums we check for
 pub const BEGIN_UNWIND: [&'static str; 3] = ["std", "rt", "begin_unwind"];
+pub const BTREEMAP_ENTRY_PATH: [&'static str; 4] = ["collections", "btree", "map", "Entry"];
 pub const BTREEMAP_PATH: [&'static str; 4] = ["collections", "btree", "map", "BTreeMap"];
 pub const CLONE_PATH: [&'static str; 2] = ["Clone", "clone"];
 pub const COW_PATH: [&'static str; 3] = ["collections", "borrow", "Cow"];
 pub const DEFAULT_TRAIT_PATH: [&'static str; 3] = ["core", "default", "Default"];
+pub const HASHMAP_ENTRY_PATH: [&'static str; 5] = ["std", "collections", "hash", "map", "Entry"];
 pub const HASHMAP_PATH: [&'static str; 5] = ["std", "collections", "hash", "map", "HashMap"];
 pub const LL_PATH: [&'static str; 3] = ["collections", "linked_list", "LinkedList"];
 pub const MUTEX_PATH: [&'static str; 4] = ["std", "sync", "mutex", "Mutex"];

tests/compile-fail/methods.rs

@@ -4,6 +4,8 @@
 #![allow(unused)]
 #![deny(clippy, clippy_pedantic)]
 
+use std::collections::BTreeMap;
+use std::collections::HashMap;
 use std::ops::Mul;
 
 struct T;
@@ -238,6 +240,18 @@ fn or_fun_call() {
     //~^ERROR use of `unwrap_or`
     //~|HELP try this
     //~|SUGGESTION without_default.unwrap_or_else(Foo::new);
+
+    let mut map = HashMap::<u64, String>::new();
+    map.entry(42).or_insert(String::new());
+    //~^ERROR use of `or_insert` followed by a function call
+    //~|HELP try this
+    //~|SUGGESTION map.entry(42).or_insert_with(String::new);
+
+    let mut btree = BTreeMap::<u64, String>::new();
+    btree.entry(42).or_insert(String::new());
+    //~^ERROR use of `or_insert` followed by a function call
+    //~|HELP try this
+    //~|SUGGESTION btree.entry(42).or_insert_with(String::new);
 }
 
 fn main() {